Discussion
A voltage ratio of 10 expressed in decibels is
Answer: B
Amplitude ratios use twenty times the logarithm, because power goes with the square of voltage:
\[ 20\log_{10}(10) = 20 \ \mathrm{dB} \]
giving 20 dB, the same figure a power ratio of 100 produces - which is exactly the point, since ten times the voltage is a hundred times the power. 10 dB would follow from using the power formula on a voltage ratio. 1 dB and 40 dB do not follow from either convention.
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